The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. DE 101 02 449.5, filed on Jan. 19, 2001, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention relates to a device for hot dispersing fibrous paper stock and a method of dispersing the stock with the device.
2. Discussion of Background Information
Devices of the above-mentioned type are used, for example, for improving the quality of fibrous stock made from recovered paper. It is known that fibrous paper stock can be homogenized by dispersion and thereby be significantly improved. Here, frequently, a fibrous scrap stock is processed having a dry matter content between 15 and 35% and brought to a temperature that is much higher than the ambient temperature. The heating necessary for this may occur by the direct addition of steam between the dispersing armaments as shown in DE 197 12 653 A1, the disclosure of which is expressly incorporated by reference in its entirety. The advantage of this measure already known is that the milling, heating, and dispersing of the scrap stock can occur in a single device. However, problems may arise if the scrap stock is not fine enough for quick heating, even in an armament.
The invention provides for a process in which it is possible to shorten the heating times even more and/or to further raise the stock temperature.
The invention provides for a dispersing machine for hot dispersing a highly consistent fibrous stock comprising at least one stationary stator that includes a plurality of annular concentric rows of stator teeth. At least one rotating rotor is provided that includes a plurality of annular concentric rows of rotor teeth. An annular dispersing zone is formed by the stator teeth and the rotor teeth whereby the rotor teeth are adapted to rotate adjacent the stator teeth such that a distance is maintained between the stator teeth and the rotor teeth in the annular dispersion zone. An inlet is provided that allows the fibrous stock to enter the dispersion machine. A milling element is centrally arranged on the rotor. The milling element is arranged near the inlet and defines a milling zone. An annular chamber is arranged between the dispersion zone and the milling zone. At least one conduit allows a heating medium to enter the annular chamber. At least one rotatable annular centrifugal row of teeth is arranged between the milling element and the annular chamber.
The fibrous stock may be a fibrous paper stock. The annular chamber may be arranged radially inwards of the dispersion zone. The at least one conduit may comprise a plurality of feeding pipes. The plurality of feeding pipes may be coupled to the stator. The heating medium may comprise a gaseous medium. The gaseous medium may comprise steam. The at least one rotatable annular centrifugal row of teeth may be adapted to rotate in a direction which is opposite to a direction of rotation of the rotor. The at least one rotatable annular centrifugal row of teeth may be adapted to rotate at a different speed than a rotational speed of the rotor. The at least one rotatable annular centrifugal row of teeth may be arranged between the milling zone and the annular chamber. The at least one rotatable annular centrifugal row of teeth may be arranged between the milling zone and the dispersion zone, the annular chamber being defined by an annular space between the at least one rotatable annular centrifugal row of teeth and the dispersion zone.
The at least one rotatable annular centrifugal row of teeth may be adapted to rotate in a different direction and at a different speed than a direction and rotational speed of the rotor. The at least one centrifugal row of teeth and the milling element may be rotatable in opposite rotational directions. A radially inner end of the dispersion zone may be defined by a radially inner row of rotor teeth. The stator may have no other rows of teeth other than those of the dispersion zone. The stator may have a planar surface that faces the annular chamber. The machine may further comprise a rotating feeding screw adapted to deliver the fibrous stock to the inlet. The machine may further comprise a carrier coupled to the at least one rotatable annular centrifugal row of teeth. The carrier may be rotatably mounted. The machine may further comprise a feed screw housing, wherein the carrier is rotatably mounted to the feed screw housing. The carrier may be adapted to be driven rotationally. The carrier may be rotatably mounted to a non-movable member. The non-movable member may comprise a feed screw housing. The carrier is one of rotatable with and connected to a feeding screw.
The invention also provides for a method of hot dispersing a highly consistent fibrous stock in a machine which comprises at least one stationary stator that includes a plurality of annular concentric rows of stator teeth, at least one rotating rotor that includes a plurality of annular concentric rows of rotor teeth, an annular dispersing zone being formed by the stator teeth and the rotor teeth whereby the rotor teeth are adapted to rotate adjacent the stator teeth such that a distance is maintained between the stator teeth and the rotor teeth in the annular dispersion zone, an inlet that allows the fibrous stock to enter the dispersion machine, a milling element centrally arranged on the rotor, the milling element being arranged near the inlet and defining a milling zone, an annular chamber arranged between the dispersion zone and the milling zone, at least one conduit allowing a heating medium to enter the annular chamber, and at least one rotatable annular centrifugal row of teeth arranged between the milling element and the annular chamber, the method comprising transporting the fibrous stock via the inlet to the milling zone, rotating the milling element to subject the fibrous stock to milling, allowing the fibrous stock to pass by the at least one rotatable annular centrifugal row of teeth, subjecting the fibrous stock to the heating medium in the annular chamber, and moving the fibrous stock through the dispersion zone.
The fibrous stock may be a fibrous paper stock. The annular chamber may be arranged radially inwards of the dispersion zone. The at least one conduit may comprise a plurality of feeding pipes. The plurality of feeding pipes may be coupled to the stator. The heating medium may comprise a gaseous medium. The gaseous medium may comprise steam. The at least one rotatable annular centrifugal row of teeth may be adapted to rotate in a direction which is opposite to a direction of rotation of the rotor. The at least one rotatable annular centrifugal row of teeth may be adapted to rotate at a different speed than a rotational speed of the rotor. The at least one rotatable annular centrifugal row of teeth may be arranged between the milling zone and the annular chamber. The at least one rotatable annular centrifugal row of teeth may be arranged between the milling zone and the dispersion zone, the annular chamber being defined by an annular space between the at least one rotatable annular centrifugal row of teeth and the dispersion zone. The at least one rotatable annular centrifugal row of teeth may be adapted to rotate in a different direction and at a different speed than a direction and rotational speed of the rotor.
The invention further provides for a dispersing machine for hot dispersing a highly consistent fibrous stock comprising at least one stationary stator that includes a plurality of annular concentric rows of stator teeth. At least one rotating rotor is provided that includes a plurality of annular concentric rows of rotor teeth. An annular dispersing zone is formed by the stator teeth and the rotor teeth whereby the rotor teeth are adapted to rotate adjacent the stator teeth such that a distance is maintained between the stator teeth and the rotor teeth in the annular dispersion zone. A feeding screw housing has an inlet that allows the fibrous stock to enter the dispersion machine. A milling element is centrally arranged on the rotor, the milling element being arranged near the inlet. An annular chamber is arranged between the dispersion zone and the milling element. A plurality of conduits are coupled to the stator for allowing a heating medium to enter the annular chamber. A rotatable carrier has at least one annular centrifugal row of teeth, whereby the at least one rotatable annular centrifugal row of teeth are arranged between the milling element and the annular chamber. The rotatable carrier is rotatably mounted to the feeding screw housing.
Utilizing this process it is possible to further mill the scrap stock in the armament so that it can be heated quickly.
The highly consistent fibrous paper stock can be inserted directly into the armament of the dispersing machine either as a compressed plug or by way of a loose, only pre-milled highly consistent stock. In both cases, the stock is then collected by the first milling stage of the dispersing rotor in the flow direction, and spun outwards radially, creating small fibrous scraps. According to the invention, it then hits a rotating centrifugal toothed wheel that, although it rotates, is not part of the dispersing rotor. This centrifugal toothed wheel defines the steam chamber radially inward, therefore, when the dispersing machine is in operation, the gaps between the teeth are largely filled with stock. After the stock enters the steam chamber, it is heated to the required temperature by introducing steam; a short heating time is sufficient due to the intense prior milling. The undesired compacting of the fibrous stock between the stationary channels is avoided. The dispersing itself, i.e., the modification of the characteristics of the stock, occurs in the dispersing zone following downstream of the steam chamber.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.
Finally, the invention is related to the subject matter disclosed in U.S. Pat. No. 6,250,573, the disclosure of which is expressly incorporated by reference in its entirety.